Data from epidemiological studies have consistently shown that elevated levels of high density lipoproteins (HDL) are an index of protection against coronary heart disease. However, the mechanism whereby HDL is involved in the prevention and or reversal of atherosclerosis is not clear. One of the mechanisms whereby HDL has been proposed to function as a protector against atherosclerosis is referred to as reverse cholesterol transport. In this system, HDL functions jointly with the enzyme lecithin:cholesterol acyltransferase (LCAT) and the cholesteryl ester transfer protein (CETP) in a system to facilitate the clearance of cholesterol from the plasma. Although reverse cholesterol transport has originally been proposed by Glomset as a physiologically essential mechanism that returns the peripheral cholesterol to the liver, much of this hypothesis remains clinically unsubstantiated. Key elements of knowledge are still lacking that would allow the linking of cholesterol efflux from cells and tissues with specific events in HDL metabolism. the purpose of the proposed symposium is to provide a forum for the exchange of ideas particularly unpublished recent findings in this area. We held a symposium in 1989 that was very enthusiastically received in the scientific community. The proposed symposium is a continuation of the effort to promote the knowledge available on the metabolism of HDL and its relationship to atherosclerosis and coronary heart disease.